R2k 2024 Soil Test

[R2k]

I've owned my house for 15 years. Renovated summer of 2023 to a complete Mazama KBG lawn. 7k sqft of lawn. Been In love w/ my lawn since 2011.

I have and always will mulch-mow...15 years. In the spring/fall, I mow 2x a week to 3x a week. In the summer, I slow down to every two weeks and try to time my cuts around when a cool period/rain period will take some of the edge off the stress from cutting.

My take on watering is dependent on how the summer is going. If it's super dry and seems it'll continue that way, I'll let the lawn go dormant because the labor with watering sucks. No irrigation system. However, since this is a first-year lawn, I do not want to let it go dormant due to drought (worried about it dying).

I'm not aware of any chronic lawn diseases in my lawn. I've had grubs bad before, but I now treat for it in the spring and it hasn't been an issue since.

I'm a synthetic fert person and I tend to focus on isolating one nutrient when needed (e.g. Ammonium Sulfate for N, SOP for K, Iron Sulfate for fe, etc.). No objection to organics, but they are more of a pain for me to source.


Goals:

My goal is to have the best looking lawn. Uniform, thick, dark green, and dependable summer health.

I'm happy with my renovation and I started it early enough that I was able to get thick coverage by winter dormancy.

I have a silty top soil with a clay subsoil (quarter-sized rocks galore).

I have been tweaking my pH from 7.0 - 7.5 down to 6.5 as my goal. I use sulfur based fertilizers and elemental sulfur (when needed, front yard is about perfect). Multi-year process. As I land on 6.5/6.6, I don't add elemental sulfur since I don't want to overshoot. Planning to treat backyard with elemental sulfur May 1st. Happy so far.

I have been concerned with the Cal to Mag percentage ratios. Early 2023, I began using gypsum to leach magnesium and add calcium to try to balance the ratios. Seems to be working, but I'm skeptical until I see a multi-test trend. Slow process. I've never limed. Last gypsum treatment was March 2023 at ~50 lbs per 1k. Planning to do another one soon, but will break the gypsum treatments into smaller batches. The back still needs more treatment, but the front is balancing out, so may not do any there. Happy so far.

I believe the potassium levels should be higher for optimal health. Probably losing some K from the gypsum reactions. I use SOP to add K. Planning to add SOP 2 lbs per 1k monthly while skipping July/Aug (summer stress/drought).

Iron levels seem to be moderate, more-so in the back. At a pH of 6.5, which is my goal, I should be able to take advantage of the iron in the soil. I want to push the ppm up for both front/back.

My OM levels are decreasing rapidly over the last couple years. Don't understand why. Not sure if Logan Labs changed their process or if tons of OM have left my soil...grass is growing great though.

I'm open to micros tweaking.

Questions:

• What Phosphorous levels should I be shooting for?

• Is 4-5% the right amount of K to shoot for in my case?

• What iron ppm should I shoot for? I love deep dark color.

• When does too high of an iron ppm become a problem for my soil?

• Iron Sulfate granules (30% fe) are what I use, how often can I apply 2 lbs per 1k? Monthly except July/August and of course frozen ground?

Thanks!



Historical tests for each yard:

[MorpheusPA]

I'm mildly surprised elemental sulfur worked that well, but you really didn't have far to go. I've see recommendations on another forum to add it to calcium pit soils with a pH of 8.2 and just shake my head. Good luck with that, but the same person recommends tossing aluminum sulfate around wholesale, so intellect is clearly lacking.

You can continue out back if you want, and let the front ride this year, or discontinue this year on both (they're well within excellent pH range). There's likely to be a lot of jockeying until things settle down, but we'll see. I could be wrong.

The normal phosphorus target is, "Around 200." That's a little flexible, by which I mean a lot flexible, by which I mean, put it somewhere over 200 without being ridiculous about it. Your front is not so far over that a bit more would hurt, but it's not necessary. I shouldn't mind seeing more in the back, however, as the slightly higher pH does make it a little less available to the grass.

Potassium is rather to moderately low. Nothing is deficient, but nothing is real pleased by that, either.

I'm giving you some options here, based on your budget and your desire to be exacting (I, personally, would not be that exacting). You could use a balanced (10-10-10 or 20-20-20) fertilizer across the entire lawn this season. Your front doesn't need the phosphorus, but it won't hurt. Or you could use a high nitrogen fertilizer out front, a starter fertilizer (high first and second number, low potassium) out back, and use potassium sulfate at 3 pounds per thousand square feet across the lawn.

Boron is a little low, but not so low I feel the need to do anything about it this year.

Iron is actually OK, if a little tad low for best color, but if you feel you want to apply iron sulfate, please feel free--every month but July and August is fine, and skip June if it's getting really hot and September if the weather isn't breaking.

Recommendation 1:

April: 3 pounds per thousand potassium sulfate across the lawn.

Late May: Apply Starter in back, High nitrogen fertilizer in front, 3 pounds per thousand potassium sulfate across the lawn.

Early September: Apply Starter in back, High nitrogen fertilizer in front, 3 pounds per thousand potassium sulfate across the lawn.

October: High nitrogen fertilizer across the lawn

Growth Ceases (if there's 3-4 weeks after the last feeding): High nitrogen fertilizer across the lawn

OR Recommendation 2:

Late May: Apply balanced fertilizer across the lawn.

Early September: Apply balanced fertilizer across the lawn.

October: Apply balanced fertilizer across the lawn (a slight break; if ground freeze is expected in November, use a high nitrogen fertilizer instead).

Growth Ceases (if there's 3-4 weeks after the last feeding): High nitrogen fertilizer across the lawn

[R2k]

Awesome, thank you so much!